全文获取类型
收费全文 | 38294篇 |
免费 | 6272篇 |
国内免费 | 2505篇 |
专业分类
电工技术 | 18351篇 |
技术理论 | 1篇 |
综合类 | 3320篇 |
化学工业 | 990篇 |
金属工艺 | 603篇 |
机械仪表 | 3804篇 |
建筑科学 | 1011篇 |
矿业工程 | 2109篇 |
能源动力 | 1242篇 |
轻工业 | 178篇 |
水利工程 | 832篇 |
石油天然气 | 2527篇 |
武器工业 | 482篇 |
无线电 | 2541篇 |
一般工业技术 | 1546篇 |
冶金工业 | 848篇 |
原子能技术 | 168篇 |
自动化技术 | 6518篇 |
出版年
2024年 | 323篇 |
2023年 | 633篇 |
2022年 | 1147篇 |
2021年 | 1409篇 |
2020年 | 1617篇 |
2019年 | 1106篇 |
2018年 | 1011篇 |
2017年 | 1369篇 |
2016年 | 1520篇 |
2015年 | 1749篇 |
2014年 | 2768篇 |
2013年 | 2103篇 |
2012年 | 3228篇 |
2011年 | 3169篇 |
2010年 | 2365篇 |
2009年 | 2596篇 |
2008年 | 2398篇 |
2007年 | 2892篇 |
2006年 | 2523篇 |
2005年 | 2083篇 |
2004年 | 1749篇 |
2003年 | 1541篇 |
2002年 | 1152篇 |
2001年 | 1107篇 |
2000年 | 869篇 |
1999年 | 697篇 |
1998年 | 444篇 |
1997年 | 342篇 |
1996年 | 276篇 |
1995年 | 257篇 |
1994年 | 159篇 |
1993年 | 114篇 |
1992年 | 98篇 |
1991年 | 85篇 |
1990年 | 56篇 |
1989年 | 35篇 |
1988年 | 25篇 |
1987年 | 14篇 |
1986年 | 6篇 |
1985年 | 4篇 |
1984年 | 4篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1980年 | 6篇 |
1979年 | 3篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1975年 | 3篇 |
1959年 | 1篇 |
1951年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 93 毫秒
1.
2.
3.
SUNShou-qun ZHAOSan-xing ZHANGWei CHANGXin-long 《国际设备工程与管理》2003,8(2):80-87
The multi-fault phenomena are common in the turbo-rotor system of a liquid rocket engine.As it has many excellent qualities,the neural network might be used to solve the problems of multi-fault diagnasis of a turbo-rotor system.First,the feature expression of a common turbo-rotor fault was studied in order to build up the standard fault pattern and satisfy the need of neural network studying and diagnosing.Then.the turbo-rotor fault identification and diagnosis problems were investigated by using a BP(back-propaga-tion)neural network.According to the BP neural network problems,the parallel BP neural network method of multi-fault diagnosis and classification was presented and investigated.The results indicated that the parallel Bp neural network method could solve the turbo-rotor multi-fault diagnosis problems. 相似文献
4.
Masami Ikeda Susumu Fukumoto Hiroshi Takao Shinya Ohtsuka Eiichi Haginomori Masayuki Hikita 《Electrical Engineering in Japan》2002,141(4):16-24
This paper describes the dielectric breakdown characteristics of oil and oil‐impregnated paper for very fast transient (VFT) voltages. Blumlein circuits generate VFT voltages of 60 and 300 ns in a pulse width that simulates disconnecting switching surges in gas‐insulated switch gears. We measured the breakdown voltages of needle‐to‐plane, plane‐to‐plane oil gaps and several pieces of paper between plane electrodes for VFT and lightning impulse voltages. The measured data were formulated in V‐t characteristics and Weibull probability distributions. The inclination n of V‐t characteristics of insulating paper is 150, which is less than n = 13.7 of the plane‐to‐plane oil gap in the VFT time range. The shape parameters of Weibull distribution obtained in this study show that the scattering of breakdown voltages of paper is much less than that of oil. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 141(4): 16–24, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10043 相似文献
5.
6.
7.
Iwao Shimizu Yuji Naito Iwao Yamaguchi Katsuyuki Kaiho Hitoshi Mizoguchi Satoru Yanabu 《Electrical Engineering in Japan》2008,164(1):52-61
Using conventional high‐temperature superconducting wire, a model superconducting fault current limiter (SFCL) is made and tested. Solenoid coil using Bi2223 silver sheath wire is so made that inductance is as small as possible and a vacuum interrupter is connected in series to it. A conventional reactor coil is connected in parallel. When the fault current flows in this equipment, superconducting wire is quenched and current is transferred into the parallel coil because of voltage drop of superconducting wire. This large current in parallel coil actuates magnetic repulsion mechanism of vacuum interrupter. Due to opening of vacuum interrupter, the current in superconducting wire is broken. By using this equipment, current flow time in superconducting wire can be easily minimized. On the other hand, the fault current is also easily limited by large reactance of parallel coil. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 164(1): 52–61, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20315 相似文献
8.
提出一种配电网电容电流测量的新方法,在零序电压互感器的开口三角侧串联一个可调电感,通过注入一个变频恒流信号寻找配电网的谐振频率,改变可调电感的数值后寻找另一谐振频率,联立2个谐振方程求解电容电流,该方法消除了电压互感器漏抗对测量的影响。开发了配电网电容电流测量仪,经模拟试验和现场测试表明,该方法具有安全、快捷、准确等特点,适用于中性点不接地或经随调式消弧线圈接地配电网。 相似文献
9.
Bingyong Yan Zuohua Tian Songjiao Shi 《International Journal of Electrical Power & Energy Systems》2008,30(5):343-360
In this paper, we propose a novel distributed robust fault detection and identification (RFDI) scheme for a class of nonlinear systems. Firstly, a detection and identification estimator—robust fault tracking approximator (RFTA) is designed for online health monitoring. A novel feature of the RFTA is that it can simultaneously detect and accurately identify the shape and magnitude of the fault and disturbance. Moreover, it takes less online training time compared with the traditional neural network based fault diagnosis schemes. For some distributed systems, a network of distributed estimators is constructed where the RFTA is embedded into each estimator. Then we use consensus filter to filter the outputs of each estimator. One of the most important merits of the consensus filter is that its outputs can dramatically improve the accuracy of fault detection and identification. Next, the stability of the distributed RFDI scheme is rigorously investigated. Finally, two numerical examples are given to illustrate the feasibility and effectiveness of the proposed approach. 相似文献
10.
改进的第三代相干算法及应用 总被引:1,自引:0,他引:1
在讨论相干技术发展及三代相干算法优缺点的基础上,介绍了改进的第三代相干算法。应用自行开发的相干软件对多个油气勘探和开发区块的三维地震资料进行处理、分析,对相干时窗长度、相关道数等参数对算法效果的影响及相干体对断层、异常地质体的识别,以及解释方法进行了探讨。应用实例证明,改进的第三代相干算法抗干扰能力强,横向分辨率高,不仅适用于倾斜地层,而且对断层尤其对小断层、异常地质体具有较高的检测能力,是油气勘探和开发的一项有效和实用的技术。 相似文献